Car wash roller

ABSTRACT

A low weight corrosion resistant car wash roller includes a plastic body. The roller also includes a shaft with a sleeve arranged thereon. A set of plastic rollers are arranged on the shaft in contact with the sleeve. A second removable fastener is arranged in the body and has a plastic idle wheel arranged on each end thereof. The roller also includes a carrier link rotatably secured to the body.

This application claims the benefit of U.S. Provisional Application No. 60/919,764, filed Mar. 23, 2007

BACKGROUND OF THE INVENTION

Car wash rollers have been known for many years in the industry. Generally, car wash rollers are completely made of a metal ie., body, rollers, shafts, etc. The metal outboard roller engages a track in the car wash while the inboard roller engages a vehicle wheel being pushed through the car wash system. The prior art also included metal idle wheels that roll along the lower track portion of the conveyer system. Adjacent to the idle wheels is arranged a metal carrier link that connects to a chain or other device that moves along the conveyer system within the car wash. Most of these prior art systems used all metal components for the entire roller. This created very heavy and hard to manufacture rollers that increased the costs to the car wash operator. Also metal on metal wearing or rubbing may have caused grinding and reduce the effectiveness, durability and life of the roller system within the conveyer system of the automatic car wash.

Therefore, there is a need in the art for an improved conveyerized car wash roller. There is also need in the art for an improved car wash roller that is ultra light weight and corrosion resistant. There is also a need in the art for a car wash roller that has its body made of a plastic material and its shafts or rods sleeved with a plastic material to ensure a plastic on plastic interface. The concept of plastic only riding on plastic within the car wash industry and metal only riding on metal is in and of itself novel and will increase the durability and effectiveness of the conveyerized car wash roller of the present invention. Furthermore, there is a need in the art for a conveyorized car wash roller that has outer wheels or outboard rollers that will ride on the conveyer deck that include a pressed on metal ring assembly over a plastic wheel to increase the durability of the outboard roller or wheel and also reduce the weight and manufacturing complexity of the overall roller assembly. There is also a need in the art for a low weight, easier to manufacture and lower cost roller that is as durable as the prior art metal rollers and even increases the durability of the rollers through less corrosion of the operating parts. There is also a need in the art for a roller that has injection molded body that will reduce the costs of manufacturing such rollers.

SUMMARY OF THE INVENTION

According to the present invention, the forgoing and other objects and advantages are obtain by a novel design for an improved conveyerized car wash roller. The car wash roller includes an ultra light weight corrosion resistant roller body that generally is made of plastic material, in one preferred embodiment the plastic material is an ultra high molecular weight polyethylene plastic, however any other plastic may also be used for the body. The body also may include a predetermined number of orifices therethrough for connecting rollers and idle wheels at opposite's ends thereof. The roller also may include a steel shaft arranged through an orifice at one end thereof and an inboard roller or wheel arranged over the shaft and outboard roller or wheel arranged over an end of each shaft and in contact with the inboard roller on one surface thereof. On the opposite end of the car wash roller may be arranged a first and second idle wheel that is arranged on a shaft arranged through an orifice of one end of the roller body. Engaged with the shaft contacting the idle wheel is a carrier link that may be used with a chain within the conveyor system of the auto car wash.

Other objects, features and advantages of the present invention will become apparent from the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a car wash roller according to the present invention.

FIG. 2 shows a top view of an alternate embodiment of a car wash roller according to the present invention.

FIG. 3 shows an exploded view of a car wash system according to FIG. 2.

FIG. 4 shows a body of a car wash roller according to the present invention.

FIG. 5 shows a plan view of the car wash roller according to the FIG. 2.

FIG. 6 shows a plan view of the car wash roller according to the FIG. 2.

FIG. 7 shows a partial exploded view of the car wash roller according to FIG. 1.

FIG. 8 shows a plan view of the car wash roller according to FIG. 1.

FIG. 9 shows a plan view of the car wash roller according to FIG. 1.

FIGS. 10 a-10 d show multiple views of a car wash body roller according to the present invention.

FIGS. 11 a-11 d show multiple views of a car wash body according to the present invention.

FIGS. 12 a-12 d show multiple views of a car wash body according to the present invention.

FIGS. 13 a-13 d show multiple views of a car wash roller body according to the present invention.

DESCRIPTION OF THE EMBODIMENT(S)

Referring to the drawings, FIGS. 1-13 show contemplated embodiments of a conveyorized car wash roller 20 according to the present invention. The car wash roller 20 can be used in any know conveyorized car wash system that includes a conveyor system for pushing or pulling an automatic vehicle through an automatic car wash system. It should be noted that the embodiments shown show two contemplated embodiments of the conveyorized car wash roller 20 according to the present invention however other contemplated embodiments exist but are not shown in the figures.

FIG. 1 shows the conveyorized car wash roller 20 according to one embodiment thereof. The car wash roller 20 includes a car wash roller body 22 that generally has a rectangular shape with a predetermined width and length. One embodiment of the present invention has a width of approximately 1-½ inches. It should be further noted that approximately 1.5 inches of plastic is generally adjacent to the shafts of the roller 20 even where a slot maybe arranged in the body 22. However, it should be noted that the width of the body 22 may be within the approximate range of ¼ inch to 4 inches depending upon design requirements of the conveyer system. The body 22 is generally made of a plastic material and in one particular embodiment a UHMW polyethylene plastic material however it should noted that any other lightweight plastic, composite, natural material, rubber, or the like may be used for the body 22 of the car wash roller 20 according to the present invention. The plastic material provides an ultra low weight, corrosion resistant, sturdy and durable car wash roller 22 unlike those of the prior art. It should be noted that in one contemplated embodiment the car wash roller 20 has a weight of approximately 10 lbs or less. Most prior art rollers generally have a weight of about 18 lbs. In prior art rollers the bodies were entirely made of a metal or steel material thus increasing the possibility for corrosion from road grime, salt and the like. The body 22 generally has an overall rectangular shape with rounded edges on each end thereof, however, any other shape may also be used. One contemplated embodiment of the all plastic body will be machined to the shape as shown. However, in another contemplate embodiment it is contemplated to injection mold the all plastic body or extrude the all plastic body depending on the design requirements and the manufacturing needs available at the time. Arranged a predetermined distance from an end of the body 22 may be a first orifice 24 and another side orifice 26 through or near the opposite end of the body 22. The orifices 24, 26 will have a predetermined diameter that will mate with and interact with a shaft 28 that may be arranged therein. It should be noted that the overall length between the centerpoint of the two orifices 24, 26 through the body 22 and the overall length of the body 22 may be of any known dimension depending on the design requirements and the conveyor system in which the car wash roller 20 will be used. It should be noted that it is also contemplated to include adjacent to the orifices 24, 26 a circumferential or ring like member or bearing surface 30 that is molded machined, extruded, fastened, etc. onto an outer surface of the body 22 to allow for proper location and engagement with an inboard roller or wheel. The circumferential member or washer 30 may increase the durability of the plastic roller body 20 in the conveyor systems environment.

Connecting orifices 32 may also be arranged through a top of the body 22 for connecting and aligning the shaft 28 with the relation to the roller body 22. In one contemplated embodiment the orifices 32 may be threaded directly in the plastic material, however in another contemplated embodiment the orifices 32 may will be lined with any type of sleeve including a plastic sleeve, a metal sleeve etc. to ensure proper durability of the roller body 22. Arranged through the side orifices 24, 26 of the all plastic body 22 are a shaft or rod 28. It should be noted that the shaft or rod 28 may be hollow shafts or solid shafts or rods depending on design requirements. It is also contemplated to have a bolt or other fastener device arranged through the orifices 24, 26 to allow for easy connection of the rollers to the body 22. The shaft or rod 28 is generally made of metal material and has threaded inner bores on both ends thereof for receipt of a bolt or other fastener to secure the rollers thereto. However, it is also contemplated to have a bolt arranged therethrough or any other type of fastening mechanism other than threads to connect the shaft 28 and rollers to the body 22. The shaft or rod 28 may be made of any other material other than metal such as hard plastic, composites, ceramics, natural materials, etc. The shaft 28 also may include an orifice through a diameter thereof that will align with the orifice 32 through the body 22 to allow for insertion of a pin, or any other type of fastener to properly align the shaft 28 and rotatably fix the shaft 28 with relation to the body 22. Any type of fastener, i.e., metal, plastic, or other non metal, can be used to attach the shaft 28 to the body 22 at this midpoint thereof.

Arranged over the shaft 28 such that it is in contact with a surface of the body 22 is an inboard roller or wheel 34. An inboard roller or wheel 34 is arranged next to one or both sides of the body 22. If the raised circumferential member 30 is arranged on the body 22 the wheel 34 may have an inner diameter that will mate with and interact with such member 30 to allow for alignment of the roller 34 and proper rotation and strength of the roller 34 with respect to the body 22. Arranged over the shaft 28 on the outer end of each shaft 28 and adjacent to the inboard roller 34 is an outboard roller or wheel 36. In one embodiment the outboard roller or wheel 36 generally may have a cylindrical or wheel like shape. However, in another contemplated embodiment the outboard roller or wheel 36 may include a sleeve 38 extending from an inner diameter of the outboard roller 36 such that the sleeve 38 has generally the same outer diameter as the inner diameter of the inboard roller 34. The sleeve 38 will help provide proper support for the inboard roller 34 and provide for a reduction in the number of parts by integrating a previously separate bearing system into the outboard roller 36. It should be noted that both the inboard and the outboard roller wheel 34, 36 may be made of the same ultra high molecular weight (UHMW) plastic and the like. It should be noted that any other plastic such as polypropylene, PVC, or any other known plastic may also be used for these parts.

It should also be noted that the metal rod or shaft 28 arranged through the orifice 24 of the body 22 in one contemplated embodiment may have a plastic sleeve 40 arranged over the entire length thereof. This will ensure that plastic rides with plastic within the car wash roller 20. The sleeve 40 may be made of any material that will allow for proper rotational friction such as polypropylene, PVC, UHMW material, polytetrafloraeythelyne, and any other type of plastic, ceramic or other material. However, it should be noted that it is also contemplated to use the shaft or rod 28 without the sleeve 40 in another contemplated embodiment. The outer diameter of the sleeve 40 generally will mimic that or be a little less than that of the inner diameter of the inner bore of the outboard roller or wheel 36. After the two inboard rollers 34 and two outboard rollers 36 are arranged over the shaft, 28 any known fastener 42 of any known materials may be arranged in each end and threaded thereon to provide rolling connection of the rollers 34, 36 to the body 22. It should also be noted that plastic or metal washers or nuts may also be used in conjunction with fasteners 42. Any know fastening technique can be used to secure the rollers 34, 36 to the shaft 28 as described above.

In another contemplated embodiment a metal sleeve 44 may be arranged over the outer portion of the outboard wheel or roller 36. The metal sleeve 44 may can have any known shape such as a simple cylindrical shape or cylindrical shape with an inboard extending ring 46. The use of the metal sleeve 44 over the end of the plastic roller 36 is contemplated in one embodiment however in another contemplated embodiment the metal sleeve 44 will not be used. The use of the metal sleeve 44 may ensure a metal to metal contact between the metal of the upper portion of the conveyor track and the car wash rollers. Generally, the sleeve 44 will be arranged over the outer surface of the wheel 36 via an interference fit. However, any other known connecting methods between plastic and metal such as plastic welding, epoxy, gluing, fasteners, or any other known technique can be used to secure on the outer sleeve which generally is made of a metal material to the plastic surface may be used.

Arranged on the opposite end of the body 22 is a metal removable fastener, shaft or rod 48 arranged through other orifice 26 therein. The removable fastener, shaft or rod 48 operates in the same general manner as that described for the other shaft above. The shaft 48 may or may not also have a plastic sleeve arranged over the outer diameter thereof in the same general manner as described above. Arranged over each end of the shaft or rod 48 is an idle wheel 50. The shaft 48 may or may not be pinned and rotatably fixed with respect to the body 22. The idle wheel 50 may be made of a plastic material and in one embodiment an ultra high molecular weight polyethylene plastic however any other plastic, composite or light weight material may also be used for the idle wheels 50. The idle wheels 50 may have a cylindrical shape with an inner bore and a predetermined sized inner diameter. The idle wheels 50 may have a predetermined width that will mimic the lower track portion of the conveyer system thus allowing for the idle wheel 50 to roll along freely in the lower track therein. In one contemplated embodiment the idle wheels 50 may have a metal sleeve arranged thereover to allow for a metal to metal contact between the wheel 50 and of the lower track portion of the conveyer system. However, in another contemplated embodiment the UHMW plastic wheels 50 may be used as such with no metal sieve arranged there over. The metal sleeve may take any of the forms such as described above.

A carrier link 52 is arranged between the plastic body 22 of the car wash roller 20 and the idle wheels 50 according to the embodiment shown in FIG. 1. The carrier link 52 may be used to connect to the chain of the conveyer system of the car wash system. The carrier link 52 may be capable of rotating the one end of the body 22 to allow for proper placement of the car wash roller 20 with respect to the wheel of the automotive vehicle and during the return of the car wash roller to the beginning of the conveyer system. Any known shaped carrier link 52 may be used. In the embodiment shown the carrier link 52 is made of a metal material however it is also contemplated to make the carrier link 52 out of any known composite, metal, ceramic or any other known material.

FIG. 2 shows another contemplated embodiment of the car wash roller 120 according to the present invention. Like numerals indicate like parts. The car wash roller 120 includes a body 122 that is made of any know plastic material in the embodiment shown, an ultra high molecular weight polyethylene plastic is used. However any other known plastic such as polypropylene, PVC, or any other know plastic rubber, ceramic, composite or lightweight material may be used for the body 122. The body 122 generally has the same dimensions as that described above. The body 122 also includes a first and second generally circular side orifice 124, 126 through an entire width thereof located at predetermined positions near each end thereof. In the embodiment shown the orifices 124, 126 generally are circular in shape however another shaped orifice may be used for these orifices. Each end of the body 122 also has a circular shaped or curved surface, however, any other shape for the ends or the body 122 may be used. This will allow for proper functioning of the roller 120 within the conveyer system. Adjacent to each orifice 124, 126 is a raised circumferential rib, bearing surface or ring like member 130. The raised members 130 generally mimic the inner diameter of the rollers or wheel that will be arranged adjacent thereto. The raised circumferential rib or members 130 extend a predetermined distance from the side of the all plastic body 122. These ribs 130 may increase the strength of the all plastic body 122 and hence the durability and longetivity of the plastic roller 120 within the car wash conveyer system. The circumferential ribs, bearing surfaces or extensions 130 may extend anywhere from 1/10 of an inch to multiple inches from each side surface of the body 122 depending on the design requirements of the inboard and outboard rollers or wheels. In one contemplated embodiment the extensions 130 extend approximately one quarter of an inch from the body 122. It is also contemplated on one end to have a connecting orifices 132 that aligns with an orifice through the side of the body 122. This orifice 132 will be used to secure a fastener to a metal shaft or rod 128 arranged within the orifice 124 of the body 122.

Arranged within the side orifice 124 is a shaft or rod 128 generally made of a metal material however any other hard plastic, ceramic, composite of the like may also be used. In one contemplated embodiment the metal rod or shaft 128 may will be hollow however in another contemplated embodiment it will be a solid piece with a machined end therein having threads to receive a fastener in each end thereof or one fastener through the entire length thereof. However, in another contemplated embodiment, the metal rod or shaft 128 may have a plastic sleeve 140 made of any known polypropylene, PVC, UFMW, Teflon or any other know plastic material arranged thereover. The sleeve 140 may be secured to shaft 128 by any known chemical or mechanical bonding methodology including but not limited molding, gluing, press fit, interference fit, welding, lasers, etc. The plastic sleeve 140 over the shaft or rod 128 may offer a plastic to plastic engagement between the parts thus plastic will ride on plastic within the car wash roller system. The rod 128 may be used with the sleeve 140 or without the sleeve 140 generally the outer diameter of the shaft or rod and sleeve combination will approximately be the same as the inner diameter, or a little less than, of the side orifice 124. Once the shaft or rod 128 is arranged within the side orifice 124 the shaft 128 may have an inboard roller or wheel 124 arranged on each end thereof and an outboard roller or wheel 136 arranged adjacent to the inboard wheel 134. The inboard roller or wheel 134 will be arranged such that it will be in contact with an outer surface of the body 122. The out board wheel 136 may arranged over the shaft 128 such that it will be in contact with an end surface of the inboard roller or wheel 134 on one end thereof. In one contemplated embodiment the outboard wheel 136 may have a predetermined outer diameter and a predetermined inner diameter bore therein. In another contemplated embodiment extending from one end of the outboard roller 136 may be a sleeve like member 138 with an outer diameter generally the same as the inner diameter of the inboard roller 134. Both the inboard rollers 134 and the outboard rollers 136 are generally made of the same UHMW plastic as described for the body 122. In one contemplated embodiment the shaft 128 may be fixed with relation to the body 122 via the connecting orifice 132 and a fastener arranged there through. After both the inboard and the outboard roller or wheels 134, 136 are arranged over the shaft 128 a fastener 142 will be arranged in each end of the threaded shaft 128 to secure the rollers 134, 136 to the shaft 128 and hence plastic body 122. This will allow for an ultra lightweight corrosion resistant roller 128 that has plastic riding on plastic and metal riding on metal.

Arranged on the opposite end of the body 122 of FIG. 2 is a predetermined shaped slot 160. The slot 160 is arranged at a midpoint along a longitudinal length of the body 122. The slot 160 will extend a predetermined distance into the body 122 and will have a predetermined angled surface 162 emanating from a midpoint in both directions thereof from. In one contemplated embodiment the angle will be approximately 47 degrees. However, it should be noted that the angle can be anywhere from 0 degrees to 360 degrees depending on the design requirements of the car wash roller 122. The slot 160 may have a predetermined width such that the width will accommodate any of the well known carrier links 152 therein and will allow for carrier link 152 to rotate in a predetermined arc. The predetermined angle surfaces 162 of the slot 160 will ensure that the carrier link 152 will engage with the slotted surface 162 to create a stop surface thus keeping the carrier link 152 from engaging the outer surface of the body 122 thus possibly reducing the durability and the longetivity of the car wash roller 122 in the conveyer environment. A second slot 164 may also be arranged a predetermined depth into the body 122.

Arranged within the orifice 126 at the slotted end of the roller body 122 is a metal shaft or rod 128 as described above. The shaft or rod 128 may have a plastic sleeve 140 as described above. Arranged over each end of the shaft or rod 128 may be a UHMW plastic idle wheel or roller 150. The idle wheel or roller 150 may have a generally cinderlical shape within an inner bore with a predetermined diameter that will engage with and mate with the outer bore of the shaft or rod 128 and/or the sleeve 140 depending on the embodiment. After each wheel 150 is arranged thereon the inner portion of the wheel 150 may engage with an outer surface of the body 122 thus leading to a plastic to plastic engagement therein. The inner diameter of the idle wheels 150 may generally mate with and mimic that of the diameter of the bearing member 128 extending from each side surface of the body 122 around the side orifice 126 there through. This will ensure that the wheel 150 will roll in a predetermined plane with respect to the plastic body 122 of the roller. After the idle rollers 150 are arranged thereon a fastener will be arranged in each end of the shaft 128 to secure the idle wheels 150 to the body 122.

Arranged within the slot 164 of the contemplated embodiment of the car wash roller 122 is any known carrier links 152. The carrier link 152 may generally have a width that will be slightly less than the width of the slot 160 within the end of the plastic body 122. The carrier link 152 may have an orifice that will be arranged over the rod 128 arranged through the second side orifice 126 of the all plastic body 122. This will allow for the carrier link 152 to rotate completely around the end of the body 122. It is also contemplated to use a metal sleeve over the outer plastic wheels and the idle wheels 150 as was used described above for the outboard roller wheels 136. Therefore, in one contemplated embodiment the sleeves as described above may be pressed fit, glued, directly molded thereon or connected via any other known fastening technique, either chemical or mechanical, to the outer surface of the idle wheels 150. However, it is also contemplated to use the idle wheels 150 with the plastic surface only.

Therefore, the conveyer car wash roller 120 uses an ultra lightweight corrosion resistant plastic, such as a UHMW polyethylene, to create the body of the roller, the idle wheels, the inboard rollers, and the outboard rollers. This will greatly reduce the weight of the roller 20 with respect to prior art car wash rollers. Furthermore, the shaft and rod generally will be metal along with the carrier links thus not effecting the durability and longetivity of the plastic car wash roller 20 according the present invention. Also it will allow for plastic to plastic interaction within the car wash roller 20 and metal to metal interaction with the car wash roller 20. It is also contemplated that the metal sleeve 44 over the outboard roller 36 and the idle rollers 50 will further increase the longetivity of the all plastic outboard and idle rollers. Generally, the sleeves 44 would be made of a metal material to ensure metal to metal contact with the conveyer tracks within the conveyer system. The use of the metal sleeve and plastic wheel will reduce the weight and cost of the car wash roller with those of comparable prior art all metal car wash rollers. Also the use of the plastic body and plastic components will reduce the tolerances between parts in the conveyer system thus increasing durability, longetivity and increased efficiency of the car wash system for the car wash operator. It should be known that it is contemplated to injection mold all of the plastic parts including the body and wheels. However, it is also contemplated to extrude any of these parts and to machine these parts to there predetermined specifications depending on the design requirements and manufacturing facilities available for such construction of the plastic members.

Other contemplated embodiments may also be designed and shown from the above mentioned discussion and the attached drawings to include any known designs in the art for such conveyorized car wash rollers such that any of these contemplated rollers can be used in any of the conveyer systems in automatic car washes.

While it may be apparent that the preferred embodiments of the invention disclosed are well calculated to fill benefits, objects, or advantages of the invention, it will be appreciated that the invention is susceptible to modifications, variations and change without departing from the proper scope of the invention as shown. 

1. A car wash roller, said roller including: a plastic body; a shaft arranged in said body; a plastic sleeve arranged over said shaft and in contact with said body; a first plastic wheel arranged over said sleeve on one end thereof; a second plastic wheel arranged over said sleeve on another end of said sleeve; a second shaft arranged in said body near one end of said body; a first plastic idle wheel arranged on one end of said second shaft; a second plastic idle wheel arranged on another end of said second shaft; and a carrier link rotatably secured to said body.
 2. The roller of claim 1 wherein said shaft is made of metal and is rotatably fixed with respect to said body.
 3. The roller of claim 2 wherein said plastic body and said plastic sleeve ensures that plastic engages plastic to increase durability of the roller while greatly reducing a weight of the roller.
 4. The roller of claim 1 wherein said second shaft having a plastic sleeve arranged thereon.
 5. The roller of claim 1 further including a metal sleeve arranged over an outer portion of said first plastic wheel and said second plastic wheel.
 6. The roller of claim 1 further including a metal sleeve arranged over an outer portion of said first idle wheel and said second idle wheel.
 7. The roller of claim 1 wherein said first wheel and said second wheel having an inboard wheel and an outboard wheel.
 8. The roller of claim 1 wherein said plastic is an ultra high molecular weight plastic.
 9. The roller of claim 1 wherein said plastic body, said plastic wheels, said plastic sleeve and said plastic idle wheels allow for a lightweight, corrosion resistant, low cost and durable roller which increases efficiency of the car wash roller.
 10. The roller of claim 1 wherein the car wash roller is less than approximately ten lbs in total weight.
 11. The roller of claim 1 wherein said body having a slot arranged along a midpoint thereof.
 12. The roller of claim 11 further including a raised ring-like member extending from a surface of said body, said slot having an angled surface therein.
 13. The roller of claim 1 further including a fastener arranged through said first wheel and into said shaft to secure said first wheel to the roller.
 14. A car wash roller for use in an automatic car wash system, said roller including: a plastic body having at least two orifices through a width thereof; a shaft arranged in one of said orifices; a plastic sleeve arranged over an outer surface of said shaft; a first plastic wheel arranged over said sleeve on one end thereof; a second plastic wheel arranged over said sleeve on another end of said sleeve; a second shaft arranged in another of said orifices near one end of said body; a first plastic idle wheel arranged on one end of said second shaft; a second plastic idle wheel arranged on the other end of said second shaft; and a carrier link rotatably secured to said body.
 15. The roller of claim 14 wherein said shaft and said second shaft are made of a metal.
 16. The roller of claim 14 wherein said plastic is an ultra high molecular weight material.
 17. The roller of claim 14 further including a metal sleeve arranged over an outer portion of said wheels and said idle wheels.
 18. The roller of claim 14 wherein said first wheel and said second wheel having an inboard wheel and an outboard wheel.
 19. The roller of claim 14 wherein the use of plastic creates a corrosion resistant, more durable and efficient roller that weighs approximately ten pounds.
 20. The roller of claim 14 wherein the car wash roller ensures plastic engages plastic and metal engages metal throughout the car wash system. 